Wave energy converters are known in the art and employ a variety of wave energy conversion mechanisms. However, unlike offshore wind turbines, ocean wave energy converters have not hitherto been deployed in large numbers for providing electrical power to electrical supply networks. A contemporary challenge is to implement aforesaid ocean wave energy converters in a cost effective manner, whilst ensuring that they convert ocean wave energy efficiently to electrical power and also survive severe weather conditions which are occasionally encountered offshore. The challenge thus has associated constraints which can be mutually opposing, for example a robust design of ocean wave converter is potentially more costly to manufacture and deploy in comparison to a less-robust structure.
A robust and efficient wave energy converter is described in a published international PCT patent application no. WO2011/162615A2 (PCT/NO2011/000175, “Ocean Wave Energy System”, Havkraft AS, Geir Solheim) which is hereby incorporated by reference. The wave energy converter is implemented as an ocean wave energy system for generating power from ocean waves, wherein the system includes a platform supporting an array of hollow columns whose respective lower ends are in fluidic communication with ocean waves and whose respective upper ends are in air communication with a turbine arrangement such that wave motion occurring at the lower ends is operable to cause air movement within the columns for propelling the turbine arrangement to generate power output. The system further includes one or more position-adjustable and/or angle-adjustable submerged structures near the lower ends of the columns for forming ocean wave propagating in operation towards the lower ends of the columns to couple the waves in a controllable manner into the hollow columns.
In the aforesaid published PCT application no. WO2011/162615A2, there is provided a comprehensive overview of wave energy theory which is hereby incorporated by reference. Ocean waves are surface waves substantially at an interface between two fluids, namely ocean water and air. The surface waves propagate substantially within a plane of the interface and are susceptible to being refracted, reflected, transmitted and absorbed at any objects intersecting substantially with the plane of the interface. For the surface waves to be absorbed effectively, the objects must be wave impedance matched to an impedance of the surface waves. When the objects are of a physical size comparable to a wavelength of the surface waves, designing the objects to provide an effective wave impedance match is a complex task, especially when the surface waves in practice have a varying wavelength depending upon ocean weather conditions. In addition, the objects need to be designed to withstand severe storm conditions and also be substantially free of cavitation effects when large amounts of wave energy are being absorbed by the objects. The aforesaid published PCT application describes a wave energy converter which is capable of providing efficient absorption of ocean waves. Although there are many similarities between electromagnetic wave propagation and ocean wave propagation, there are major differences on account of ocean waves having mass and being subject to fluid flow effects.
However, there arises a need to implement a wave energy converter which is especially efficient at absorbing ocean wave energy whilst also being robust in operation, and cost effective to manufacture. For example, it is desirable that the wave energy converter is manufactured in such a manner which is convenient for contemporary ship yards.